West Nile virus activity spreads across California
In the first seven months of 2015, 31 counties in California reported West Nile virus activity. This is 10 more counties than compared to the same time last year. It is also a significant increase compared to the average of 18 counties from the past five years.
As of Wednesday, 240 samples of mosquitoes had tested positive for the West Nile virus, which is six more than last year at this time.
“While there have been no human cases of West Nile virus reported so far this year, it is only a matter of time before we see the first case,” Dr. Karen Smith, CDPH director and state health officer said. “As people go outdoors to enjoy the warm weather we’ve been experiencing, we’d like them to be safe and know how to protect themselves against West Nile virus.”
Many factors impact West Nile virus rates, including the number and kinds of mosquitoes and birds in a specific region, the climate, and the strength of the immune systems in the birds near West Nile virus regions.
Experts estimate that this year’s increase is due to the drought, which has decreased water sources for mosquitoes and birds. As the two creatures find water, they are in closer contact, which increases the virus’ transmission.